1. Field of the Invention
The present invention relates to a magnetic head for use in a magnetic recording/reproducing apparatus such as a video tape recorder (VTR), a digital video cassette (DVC), a digital audio tape recorder (DAT), etc.
2. Related Art
Conventionally, a magnetic head for use in a VTR is configured, for example, in such a manner as shown in FIG. 10.
That is, in FIG. 10, a magnetic head 1 is a so-called ferrite bulk magnetic head in which a pair of ferrite cores, that is, a C-shaped core 2 and an I-shaped core 3, are made to face each other and bonded with each other by bonding glass 4 so as to form a predetermined gap portion 5 and coils (not shown) are respectively wound in winding grooves 2a and 3a which are provided respectively in the cores 2 and 3.
Here, as shown in FIG. 11, with respect to the gap portion 5, track width restriction grooves 2b and 3b are formed in the opposite side surfaces of the respective cores 2 and 3 in order to obtain a desired track width, and then when the cores 2 and 3 are bonded with each other, the bonding glass 4 is filled in the track width restriction grooves 2b and 3b at the same time.
Thus, a tape slide surface A is defined by the upper surfaces of the cores 2 and 3 and the upper surface of the bonding glass 4 in a manner so that the region of the gap portion 5 formed between the track width restriction grooves 2b and 3b are disposed on the way of the slide surface A.
Further, such a so-called metal-in-gap (MIG) magnetic head as shown in FIGS. 12 and 13 is also known.
In FIG. 12, a MIG magnetic head 6 is formed in such a process that after metallic magnetic films 7a and 8a are deposited on bonding surfaces of a pair of cores 7 and 8 made from Mn--Zn ferrite, the bonding surfaces are made to face each other so as to be bonded with bonding glass 4 to thereby form a gap portion 9 of a predetermined gap width, and coils (not shown) are wound in winding grooves 7b and 8b formed in the respective cores 7 and 8.
Here, as shown in FIG. 13, with respect to the gap portion 9, track width restriction grooves 7c and 8c are formed in the opposite side surfaces of the respective cores 7 and 8 in order to obtain a desired track width, and then when the cores 7 and 8 are bonded with each other, the bonding glass 4 is filled in the track width restriction grooves 7c and 8c at the same time.
Thus, a tape slide surface A is defined by the upper surfaces of the cores 7 and 8 and the upper surface of the bonding glass 4 in a manner so that the region of the gap portion 9 formed between the track width restriction grooves 7c and 8c are disposed on the way of the slide surface A.
In each of the thus configured magnetic heads 1 and 6, however, there is such a problem as follows.
In the magnetic head 1 (6), since the cores 2 and 3 (7 and 8) are bonded with each other after formation of the track width restriction grooves 2b and 3b (7c and 8c), there is a possibility that the track width restriction grooves 2b and 3b (7c and 8c) of the cores 2 and 3 (7 and 8) are displaced from each other as shown in FIG. 11 (FIG. 13), so that at the time of recording/reproducing by means of the magnetic head 1 (6), noise may be generated by magnetic flux leakage from such track displacement portions d so as to make it impossible to perform accurate signal recording/reproducing. Particularly in the case of a magnetic head for DVC or the like having a narrow track width, there is a fear that it becomes impossible to perform recording/reproducing per se by the track displacement portions d.
In this regard, for example, a magnetic head having such a configuration as shown in FIG. 14 is known.
In FIG. 14, a magnetic head 10 is formed in such a process that after the cores 2 and 3 are bonded in the magnetic head 1 of FIG. 10, the regions of the track width restriction grooves 2b and 3b are removed along the longitudinal direction of the tape slide surface A so that the track width restriction grooves 2b and 3b pass the opposite sides of the gap portion 5 to thereby prevent occurrence of track displacement of the gap portion 5, bonding glass 11 is filled in the removed regions, and the opposite sides of the bonding glass 11 are removed to thereby form steps 12.
In such a magnetic head 10, while it is possible to suppress the occurrence of track displacement, there arises a problem in practical use that the bonding glass 11 is worn away early in use because the bonding glass 11 having low abrasion resistance is exposed widely with respect to the tape slide surface A.